The cotyli are separated by a smooth ridge, that is highest at its posterior termination. The tuberosity is high and massive, with a wide depression on its top for the reception of the ligament of the patella; the sides are deeply pitted by venous foramina. A section of the shaft at the lower part of the tuberosity would be subtriangular; while below it becomes more cylindrical, as it becomes smaller, reaching its shortest diameter about three fifths down the shaft. Below this it expands and forms the large subcircular distal end. The articular face is concave, with a slight, smooth ridge running fore-and-aft on its internal side. The malleolus is broad and low. The _fibula_ is distinct, but very slender; its proximal end has a small circular face, which articulates with the tibia on a facet developed on the bottom of a projection of the tuberosity; the distal end is much flattened, but enters into the ankle-joint. _Measurements of the Tibia._ M. Transverse diameter of proximal articulation ·158 Longitudinal diameter of proximal articulation ·123 Smallest circumference of shaft ·16 Greatest distal circumference above the articular face ·308 Diameter of distal articulation longitudinally ·082 Diameter of distal articulation transversely ·130 Width of tuberosity below pit for ligament of the patella ·075 Uintatherium princeps, _sp. nov._ Established on several portions of the head, vertebral column, and the limbs. This species may readily be distinguished from the last by its larger size, the broad nasals with small tuberosities, the stronger zygomatic arches, and the sub-cylindrical centra of the dorsal vertebræ. The _nasals_ are broad and flat for some distance behind the tuberosities. Although the animal was not adult, the nasal suture is almost obliterated, and is visible only on the inferior surface; in this respect it is very different from the _U. leidianum_, in which the suture persists throughout life; as is shown by the type specimen, which was past maturity. The tuberosities of _U. princeps_ are lower, broader, and more everted than in the preceding species; are not divided by a groove, but united together by a low rounded ridge, to which the surface of the nasals gradually rises from behind. The portion of the bones anterior is short, stout, and projects horizontally. The _median_, or _maxillary_, _projections_ are apparently short and everted; they are somewhat compressed antero-posteriorly, and enlarge rapidly downwards. They are transversely oval in section.